PROBLEM TO BE SOLVED: To provide a device for allowing healthy cells to survive and selectively killing microorganisms.SOLUTION: A device equipped with a lamp module 1 having a light source for emitting a pulse light with a wavelength band of at least 200-2,000 nm allows healthy cells irradiated with a pulse light to survive, the energy density of the pulse light being 65.00 J/cmor less in the entire wavelength band in a pulse light irradiated area, and selectively kills microorganisms irradiated with the pulse light.SELECTED DRAWING: Figure 1